1. Technical Field of the Invention
The present invention relates generally to a high speed digital clock circuit that produces multiple clock frequencies, and particularly to a wireless communication system using the clock circuit, one such system being the Multi-Band Orthogonal Frequency Digital Modulation (OFDM) Alliance (MBOA) Ultra Wideband (UWB) system.
2. Description of the Prior Art
Digital clock generation is used in digital electronic systems to maintain synchronism of processes. In the MBOA UWB system, several radio frequency (RF) clock frequencies subject to severe timing restraints are needed in the transceiver circuitry. Clock generators are typically used to generate one or more clocks employed by various circuits in the system. A voltage-controlled oscillator (VCO) is typically used to generate a clock signal. Some constraints of VCOs include tuning range and potential interference in frequency bands of interest due to harmonic spurs. Improved design of a clock generation scheme can achieve an optimized system in terms of power consumption, tuning range, form factor and manufacturing cost.
Existing digital clock generators have used a three voltage controlled oscillator design to provide the three required clock frequencies. Such a design is straightforward, but it suffers from high power consumption and has a large form factor. Form factor refers to the size, configuration, or physical arrangement of the circuit. A larger form factor generally relates to high manufacturing costs.
Another prior art digital clock generator uses two voltage controlled oscillators combined with a mixer. Although not as straightforward as using voltage controlled oscillators to generate the needed three clock frequencies, this design requires only two voltage controlled oscillators. However, two voltage controlled oscillators still consume significant power, while resulting in a large form factor and high manufacturing costs.
What is needed is a clock frequency generator with reduced power consumption and form factor, as well as lower manufacturing costs.